Anterior lumbar interbody fusion (ALIF) has become an increasingly useful approach for fusing the lumbar spine. With ALIF procedures, a disk between adjacent vertebrae is removed and a fusion cage implant is inserted into the disk space. Through known techniques, bone growth through and around the cage is promoted to fuse the adjacent vertebrae together. In one ALIF procedure, a condition known as spondylolisthesis A can be treated (FIG. 1) by removal of the disk D between the sacrum (S1) and the adjacent lumbar vertebrae (L5). Other disk spaces between other adjacent disks can also be treated with this ALIF procedure.
There is some inherent difficulty in placing screws between the cage and a higher vertebra in the spine to fix the cage in place, particularly when fusing L5 and S1, and when the L5-S1 disk orientation is more angled toward the pubis rather than horizontally situated. Because of such angularity, upwardly angled bone screw supporting bores in the cage cannot be readily accessed. Accordingly, a need exists for a superior method for securing the interbody fusion cage implant to adjacent vertebrae which can be accessed conveniently in a wider variety of anatomical presentations for adjacent vertebrae to be fused.